Safety stop and switch



April 15, 2 1,490,788

J. W. THROPP SAFETY STOP AND SWITCH Filed March 17 1923 4 Sheets-Sheet 1 April 15, 1924. 1,490,788

' J. w. THROPP SAFETY STOP AND SWITCH Filqd March 17 1923 4 sheets sheet, 2

April 15, 1924. J. W. THROPP SAFETY STOP AND SWITCH 1923 4 Sheets-Sheet 5 Filed March 1'? Patented Apr 15, 1924.

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PATENT JOSEPH W. THROPP, F TRENTON, NEW JERSEY.

SAFETY STOP AND SWITCH.

Application filed March 17, 1923.

To aZZ whom it may concern:

Be it known that I, JOSEPH IV. THROPP, a citizen of the United States, residing in Trenton, Mercer County, New Jersey, have invented a Safety Stop and Switch, of which the following is a specification.

My invention relates to control mecha nisms, and more particularly, to safety control mechanisms.

In its broadest aspect, one object of my invention is to provide, in combination with a mechanical and an electrical safety stop for machinery, additional safety mechanism which insures that the machinery is in proper condition for starting.

More specifically, an object of my invention is to provide a safety control mechanism comprising a machine to be controlled, a power supply for said machine having a circuit-interrupting device therein, safety trip mechanism for actuating the circuit-interrupting device, a brake for the machine, means for effecting the substantially simultaneous operation of the switch and the brake, and additional circuit-interrupting means for maintaining the power supply ineffective while the brake is on.

In carrying my invention into practice, it has been found that it is particularly applicable to machines having exposed rollers where there is danger of the operator being caught between the same, though it, is to be expressly understood that my invention is not necessarily limited to such apparatus.

With these and other objects and applications in view, my invention: further consists in the details of construction and operation hereinafter described and claimed and illustrated in the accompanying drawing wherein;

Figs. 1 and 2 are front and end elevational views, respectively, of one form of embodiment of my invention, as applied to a mixing machlne;

Flg. 3 1s an enlarged detail View, shown partially in section, of thedorake release mechanism and the circuit-interrupting means for preventing the starting of the machine prior to the resetting of the brake mechanism;

Figs. 4: and 5 are top plan and end elevational views, respectively, of-the structure of Fig. 3, with the-brake drum and band removed.

In the illustrated form of embodiment of my invention, shown in the drawing, where- Serial No. 625,852.

in it is applied to a so called mixing machine, a pair of horizontally positioned cooperating rollers 1 and 2 are journaled in bearing boxes 3 and 1, respectively, which are slidably mounted in a pair of vertically positioned housings 5 and 6, which are supported on a base frame 7. One of the rollers, say 1, is provided with a projecting shaft portion 8 which extends beyond the housing 5 and carries a gear wheel 9. The gear wheel 9, in turn, meshes with a driving pinion 11 which is mounted at one end of a power shaft 12, a gear wheel 13, which meshes with a driving pinion'l i of a dynamo electric device 15, being mounted at the other end thereof.

A brake drum 16 is rigidly secured to the power shaft 12 and it is provided with a co operating brake band 18 having one end rigidly secured to a pin 19, which is secured between oppositely positioned walls 21 and 22 of a supporting device 23 mounted on the bed plate 7. The other end of the brake band 18 is securedto a brake actuating lever 2 1 through an adjustable block and bolt mechanism 25 of known design. The brake lever 24 is secured to a pin 26 which is journaled in the opposite side portions 21 and 22 of the member 23. The other end of the brake arm 24 is provided with an adjustable weight 27 for causing the brake arm24 to assume the dotted line position shown in section 3, at which position, the brake band 18 frictionally engages the brake drum 16 to such extent as to prevent the turning of the driving shaft 12.

A bell-crank lever 28 having arms 29 and 31 is pivotally mounted on one of the side portions, say 21, of the supporting member 23 in such position that an open slot 32, which is provided in arm 29, engages a pin 33 carried by the brake'arm 2 1, thereby holding the brake arm 24: in a position where the brake is ineffective. The pin 33 may be resiliently held in the slot 32 by a spring 3 1 which extends from the side member 21 to the arm 31 of the bell-crank lever 28. may readily be seen, when the arm 31 of the bell-crank lever 28 is raised, the brake arm 24 is released, the weight 27 forcing the same downwardly and causing the brake band 18 to' frictionally engage the drum 16.

The circuit-interrupting mechanism for the motor 15-and the tripping mechanism for the brake drum 16 comprise a shaft 35 which is rotatably mounted above the rollers '3 and 4 on standards 36 and 37, which are respectively mounted on the bearing housings 5 and 6. A pair of arms 38, which are rigidly secured to the opposite ends of the shaft 35, have their outer ends connected by a rod 39 adapted to be grasped or knocked by a person desiring to stop the machine. The shaft 35 is also provided with a toothed segment 10 which co-acts with a similar member 11 rigidly secured to an arm 42 pivotally mounted on a shaft 13 carried by the supporting standard 36. A similar toothed mechanism may be supported from the other standard 37, a-rod 1 1 corresponding to the rod 39 interconnecting the ends of said levers 42.

The trip mechanism just described is operatively associated with that of the brake mechamsm herembefore mentioned by providing the shaft 35 with an extension and interconnecting a lever 45, which is carried at one end of the extension, with the arm 31 of the bell-crank mechanism 28 by means of a connecting "link 46. In View of this construction, when either of the rods 39 or 44: are caused to move downwardly, as by a person striking the same, the arm 31 of the bell crank mechanism 28 is raised withdrawing the pin 33 from the slot 32 and resulting in the setting of the brake mechanism.

' In the particular embodiment of my invention shown in the drawing, a circuit-interrupting device 47 for the motor 15 is carried by a bracket 48 which is secured to the pedestal 37 in such position that the moving element (not shown) of the switch 17 may be actuated to open the same when the shaft 35 is moved a sufficient amount to effect the operation of the brake setting mechanism. Hence when the rods39 and 14 are moved, as by a person grasping the same, when some portion of their body is caught in the machine, the shaft 35 operates to open circuit the switch 47 and simultaneously effeet the setting of the brakeniechanism. As just pointed out, the interruption of the switch 47 open circuits the energy-supply circuit (not shown) for the motor 15 and thereby stops the same while thesetting of the brake mechanism immediately stops the operation of the machine.

In practical operation, however, considerable diificulty was experienced dueto the fact that machine operators carelessly attempted to restart the machine with the brake mechanism applied. Accordingly, a switch mechanism 49 has been provided, which is actuated the brake arm24,causing the supply circuit not s hown) to the motor 15, to be inaintained in an open cin cuit condition until the brake has been released. One way of carrying this idea into effect toprovide the}, is rigid- 13/ secured to the brake arm '24:, with anextension 51 having mounted thereona sleeve ber 58 carried; by a bracket 59, the latter being secured to the side member 21 of the supporting member 23.

Assuming the brake mechanism to be set and the brake lever 24c in the dotted line position indicated in Fig. 3 of the drawing, it is seen that the movable contact elements 53 and 54 of the switch mechanism 49 are actuated out of engagement with the co-operating stationary contact elements 55 and 56, respectively, thereby establishing a break in the supply circuit (not shown) to the motor 15. in addition to that provided by the switch 4-7. \Vhen it is desired to start the machine, the brake arm 24 must be actuated into the solid line position shown in Fig. 3, where the relatively, stationary and movable contact elements of the switch 49 are actuated into engagement with each other. to complete that portionof the motor circuit containing the same. The. resetting of the brake arm 24 in the solid line position'also substantially simultaneously effects the closing of the switch 47, thereby resulting in the energization of the motor 15 and the operation of the machine.

lVhile I have described a specific embodiment of my invention, as applied to a particular type of machine. for the purpose of describing the details of construction and principle of operation thereof, it is apparent that various changes and modifications may be made therein without departing from the spirit of my invention. I desire therefore, that only such limitations shall be imposed therein asare indicated in the appended claims or as are demanded by the prior art.

I claim:

1. The combination with a power shaft to be controlled and a power source therefor,

of releasable gravity set brake apparatus operatively associated with said'power shaft, and a switch actuated by said brake apparatus for interrupting or closing said power source, and vice versa.

2. In a controlling mechanisnnthe combination with a power shaft, of gravity set brake apparatus operatively associated therewith, said apparatus having operative and inopertive positions, a brake lever for caus ing said operative and inoperative positions, and circuit-interrupting means adapted to be actuated by a movement of said brake lever from one positionto the other.

3. In a controlling mechanism, the combination with a power shaft, of a drum operatively associated therewith, a brake "banacmied by said. dramga'suppdrt "providing a rigid connection for one end of said brake band, a brake lever pivotally mounted on said support and rigidly secured 'to the other end of said brake band, and circuitinterrupting means actuated by a movement of said brake lever.

4. In a controlling mechanism, the combination with a machine, of a power-source therefor, braking means having operative and inoperative positions, whereby said power source may be rendered effective or ineffective to operate said machine, and switching means actuated in accordance with the operation of said braking means for insuring the setting of the brake in an operative position prior to the operation of said power source.

5. In combination, a machine, a power supply for said machine, a circuit-interrupting device for controlling the operativeness of said power supply, trip mechanism for actuating said device, a brake for said machine, means for effecting substantially simultaneous operation of said switch and brake and means for maintaining said power supply ineffective while said brake is effective.

6. In combination, a machine, means for driving the machine, a circuit-interrupting device for controlling the operation of said driving means, a releasable brake for said machine, safety mechanism operatively associated with said switch and brake for causing the operation of the brake substam tially simultaneous with the operation of the switch, and a second circuit-interrupting device for controlling the operation of said driving means adapted to be actuated by the operation of said brake, whereby the release of the brake prior to the operation of the driving means may be insured.

7. In a controlling mechanism, a machine, a

mechanism effects the operation of the circuit-interrupting device and the brake mechanism, and a switch actuated by said weighted lever for preventing the operation of the dynamo electric device prior to the release of the brake.

8. In a controlling mechanism, the combination with a machine, a motor for driving the machine and a power shaft interconnecting the same, of a switch for controlling said motor, trip mechanism for actuating said switch, a bell crank lever having one arm operatively associated with said trip mechanism, the remaining arm of said bell crank lever being slotted, a brake drum secured to said shaft, a brake band on the drum, a pivoted weighted lever secured to one end of said band and carrying a pin engaging the slot in said lever arm, whereby upon the operation of said trip mechanism said switch may be operated to render said motor inoperative and the weighted lever may be released to render said brake efiective to stop the machine, and a switch for insuring the release of said brake prior to the starting of the machine, said switch having relatively stationary and movable contact points, the latter being carried by said weighted lever.

JOSEPH W. THROPP. 

